Grind and inject technology disposes of waste generated by oilfield operations. The goal is to decrease environmental impact and the overall footprint of new developments. Grind and inject technology entails crushing solid waste and adding water to make a slurry which is then injected into specially permitted disposal wells, where subsurface formations trap the injected slurries. However, the effect of such injection requires the reservoir to be monitored. That is, the injection is expected to change the reservoir density over time, both near the borehole and far from the borehole. In this context, there exists a need to monitor the displacement of mass in the subsurface and, in particular, indicate if the injected material is staying near the perforation zone or is taking advantage of a path induced by the injection, such that the slurry has moved vertically in the formation.